The invention discloses a silicon-based alloy carbon composite negative electrode material, a preparation method thereof and application thereof. A core-shell structure negative electrode material isprepared with the combination of nanocrystallization and surface modification technology, a core is composed of a polymer coating graphite and a silicon-based alloy loaded on the surface of the polymer, and the shell is a cracked carbon layer. Compared with the prior art, the silicon-based alloy is uniformly loaded on the surface of the graphite by the polymer, the dispersibility of a nano-silicon-based alloy in the preparation process of a silicon-carbon composite material is improved, and the cycle stability of the composite material is improved. Moreover, the cost of raw materials is low, the preparation process of the composite material is simple, and the preparation method is environment-friendly and pollution-free.